Riot Games announced that Teamfight Tactics Mobile is coming in March 2020 but some fans will be able to play it sooner than that. Android users that didn't register yet have more chance than iOS ones who without registration.
Teamfight Tactics fans who wish to try the mobile version in beta could still pre-register on Google Store at the time of writing but unfortunately for future iOS players, they can only subscribe to news about the game.
On the other hand, Teamfight Tactics Mobile release date isn't too far away so iOS players won't be missing out on much. In fact, there is roughly only a month to go before the game becomes available to everyone as Riot stated March 2020 is the target release window .
TFT Mobile will be different from the already existing PC version in several aspects. It will have a different client that will initially support social and ranked systems as well as the progression pass. The experience will be streamlined but more functionality will be added over time.
The visual style will be somewhat altered in order to make the game clearer compared to the PC version since observing the board is not the same on six and 24-inch screens.
Most importantly, the interface will be changed in order to make it "finger-friendly" so it will have a separate inventory panel where players will be able to drag and drop items to combine and equip them. The champion shop will not be open all the time like on PC since it can obstruct the battlefield on a small screen. To that end, players will have a button to pop the shop up or down.
Unfortunately, Riot didn't find a solution for in-game chat just yet. Having a chat tab and virtual keyboard open would once again compromise battlefield visibility so neither will be supported for the time being.